Lead, a heavy metal with a notorious reputation for causing severe health problems, has been used for centuries in everything from cooking pots and plumbing to lead shot for hunters.
But lead ammunition may be going the way of leaded gasoline, as an increasing number of wildlife conservationists and public health experts support the use of non-lead ammo, sometimes referred to as "green bullets."
In October, Gov. Jerry Brown of California signed into law AB 711, a bill banning the use of lead bullets by hunters. The meat from game killed with lead bullets poses dangers to people eating it, and the lead in animal carcasses left in the field can harm other wildlife, such as the endangered California condors that live on carrion. [5 Milestones in Gun Control History]
"We are thrilled that Governor Brown has made AB 711 the law of the land," State Assemblyman Anthony Rendon said in a statement. "There is simply no reason to continue using lead ammunition in hunting when it poses a significant risk to human health and the environment."
Lead in the environment can also leach into soil and groundwater, making drinking water supplies unsafe.
Sportsmen take aim
But the ban has some members of the hunting community up in arms. "This bill, over the next five years, will end hunting in California as we know it," Sam Paredes, director of the Gun Owners of California, told Fox News. The group claims there are no viable alternatives to lead ammunition.
The California Fish and Game Wardens' Association, in joining the opposition to the lead-ammo ban, broke ranks with the state's Department of Fish and Wildlife, which officially supports the ban.
"California Game Wardens are on the front line enforcing the ban on lead ammunition for most hunting in [California] condor range," the association wrote in a letter to the governor. "But there is insufficient data to justify such a drastic action across the entire state."
Other groups — most notably, the U.S. military — are phasing out lead ammunition in favor of lead-free, green bullets. Starting in 2010, the military began to switch to lead-free versions of 5.56 mm and 7.62 mm bullets. Advocates say this move has eliminated thousands of tons of lead from the environment.
"If non-lead ammunition is good enough for the U.S. military, with all their ballistics and performance testing, it should be good enough for hunters," George Fenwick, president of American Bird Conservancy, said in a statement.
Other hunting groups are actively encouraging their fellow hunters to consider using green bullets, which are usually made of copper or copper alloys. A group of avid sportsmen has developed a website, HuntingWithNonLead.org, which espouses the virtues of non-lead ammo.
"The idea of accidentally poisoning other non-target wildlife isn't anyone's intention," the group states on their website. "But many birds and mammals feed on the … carcasses that they find during and after hunting season. In many cases, these animals unknowingly eat lead when the carcasses have been shot with lead ammo."
Bald eagles: getting the lead out
Lead takes a particularly grim toll on vultures and raptors, including golden eagles, sea eagles and bald eagles, which often scavenge for meat from game animals left in the field. (Several vulture species have been found to be more closely related to storks than to raptors like hawks and eagles, according to the Virginia Department of Game and Inland Fisheries.)
In a 2012 study published in PLOS ONE, researchers in Wyoming found that 24 percent of bald eagles had clinically significant levels of lead in their bodies during hunting season, while no eagles showed signs of lead poisoning during the off-season.
The researchers also provided non-lead ammunition to hunters during the 2009 and 2010 hunting seasons to determine the effect of switching to green bullets. "We found the use of non-lead ammunition significantly reduced lead exposure in eagles, suggesting this is a viable solution to reduce lead exposure in eagles," the study authors wrote.
Despite bans on lead in ammunition, paint, gasoline and other sources, lead poisoning remains a real concern, especially to children and unborn babies in developing countries, where lead regulations — if they exist at all — are rarely enforced.
In humans, exposure to lead can result in problems with neurological development and cognitive functioning, kidney disorders, nerve damage, cardiovascular problems and reproductive disorders.